Drivers in a thin film transistor liquid crystal display (TFT-LCD) mainly comprise a gate driver circuit and a data driver circuit. The gate driver circuit converts an inputted clock signal through shift register units and then supplies the converted clock signal on gate lines of a liquid crystal display (LCD) panel. The gate driver circuit can be formed on the LCD panel together with TFTs in a same process. The gate driver circuit comprises a plurality of stages of shift register units, and each stage of shift register unit is connected to a corresponding gate line and outputs a gate driving signal. The respective stages of shift register units are connected each other, a start signal is input to the first stage of the respective stages, and gate driving signals are output to the gate lines sequentially. An input terminal of a present stage of shift register unit is connected to an output terminal of a previous stage of shift register unit, and an output terminal of a next stage of shift register unit is connected to a control terminal of the present stage of shift register unit.
The above structured gate driver circuit is set on the LCD panel. At present, in a gate driver circuit design, a pull-down node is generally arranged to pull down the potential at an output terminal of a shift register unit not corresponding to a row to which a gate driving signal is output. However, if the pull-down node is in a direct current (DC) high level operation state for a long time, it would cause drifts in threshold voltages of relevant thin film transistors, which has a disadvantageous effect on noise reduction. On the other hand, if the voltage signal at the pull-down node is a alternate current (AC) signal, effect caused by the drifts in the threshold voltages may be reduced, however output errors may occur and in turn reading and writing errors may be generated since there is a interval in the operation of pulling down with the alternate current signal.